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K A Smirnov

Publications and source records attributed to K A Smirnov.

18 recordsLinked to original sources
PubMed1978

[Identification and study of sympathoactivating neurons of the medulla oblongata].

The neurons with descending axons which activate the lateral horn sympathetic preganglionic (vasomotor) neurons were searched in the lower brain stem of the cat. Localization of these sympathoactivatory neurons in the limit zone of medulla was outlined by means of scanning stimulation. The identification of single bulbar sympathoactivatory neurons was based on the recording of their antidromic discharges elicited by stimulation of descending sympathoactivatory pathways with conduction velocity about 4--8.9 m/s in the dorsolateral funiculi of the cervical spinal cord. The neurons studied have a very low frequency spontaneous discharges (0.1--1.0 imp/s) unrelated with cardiac and respiratory cycles. The alterations of spontaneous discharge frequency were in strict correlation with pressor phases of Maer waves and pressor reflex reactions. The inhibitory effects of the baroreceptor nerve stimulation on spontaneous and elicited discharges of these neurons were never seen. A possible role of the sympathoactivatory neurons identified as an output elements of the bulbar "vasomotor" centre is discussed.

Animals↗
PubMed1978

[Further study of the descending sympathoactivating pathways of the dorsolateral funiculus of the spinal cord].

The localization and conduction velocities of descending pathways which activate the different groups of sympathetic preganglionic nerons were studied in the cat cervical spinal cord. Certain evidences have been obtained that the fibres located near the dorsal surface of the dorsolateral funiculi with conduction velocities about 24--29 m/sec. can activate the ventral horn preganglionic neurons monosynaptically. In contrast to previous ideas, the sympathetic preganglionic neurons of the lateral horns seem to be activated not by different but by a single group of descending fibers with the conduction velocity 4--8.9 m/sec and localization in more ventral portions of the dorsolateral funiculus. The transmission from these fibers to the sympathetic preganglionic neurons of the lateral horns occurs in two ways: oligosynaptically (probably, disynaptically) and polysynaptically through a more complicated interneuronal chain. The sympathetic preganglionic neurons with unmyelinated axons, localized in the intermediate zone, for the first time were shown to be activated polysynaptically, probably via the same ways as the lateral horn neurons.

Animals↗
PubMed1978

[Descending vasoconstrictor fibers in the thoracic region of the spinal cord].

Analysis of the arterial pressure responses to electric stimulation of the spinal cord structures at T1 to L3 showed two zones of the maximal pressure activity in the lateral and medial parts of the lateral funiculus. After destruction of the lateral part at T1-T2 level, a decrease in the systemic arterial pressure occurred after stimulation of the pressor zone of the vasomotor center and structures of the spinal cord at the levels of C5 and ischiatic nerve. These and previously obtained data suggest that the pressor responses to stimulation of the lateral part of the lateral funiculus of the spinal cord are of the reticulospinal origin. Participation of the propriospinal fibers in the pressor responses to stimulation of the medial zone of the lateral funiculus is discussed.

Animals↗
PubMed1976

[Responses in the superior thoracic white rami communicantes to stimulation of the dorsolateral funiculi of the spinal cord].

In anesthetized cats, the responses in T3 white rami to stimulation of the spinal dorsolateral funiculi at C5 level displayed three typical waves. The short latency first wave is the result of stimulation of descending fibres with conduction velocity over 20 m/sec, which activate some sympathetic preganglionic neurons monosynaptically. These neurons are, probably, outside of the lateral horns and have axons with conduction velocities over 10 m/sec. The second wave is associated with the discharges of lateral horn's sympathetic preganglionic neurons disynaptically activated by descending fibres with conduction velocity about 6 m/sec.

Animals↗